By last week health officials had documented 18 cases of this strange affliction, 11 of them fatal. The cause is still unknown, but officials at the Centers for Disease Control and Prevention (CDC) have found evidence of an exotic, rodent-borne virus in some victims’ tissues. The bug, known as a Hantaan virus, spreads through the air after rats or mice shed it in their urine. It has never been linked to a disease outbreak in this country. But for now, health officials are treating it as the culprit.
The new illness has terrified the Navajo nation in recent weeks, and it’s not hard to see why. Almost every case has occurred on or near the reservation, a vast piece of desert that straddles portions of New Mexico, Arizona and Utah. And though several Anglos and one Latino have been stricken, most cases have involved Native Americans. The disease-which health authorities are calling Unexplained Adult Respiratory Distress Syndrome, or UARDS-starts with such minor symptoms as coughing, fever, muscle aches and pinkeye (unlike a cold, the syndrome doesn’t entail a sore throat or runny nose). Within 48 hours, victims start struggling for breath as their lungs fill with fluid. Dr. Frederick Koster, an infectious-disease specialist who has treated six patients at Albuquerque’s University Hospital, says antibiotics and mechanical ventilators can help arrest the disease by stopping the buildup of fluid in the lungs. But if a person isn’t treated within six hours of the first breathing problems, he says, death comes fast.
Health authorities moved briskly to investigate the outbreak. Within days of Merrill Bahe’s collapse, the New Mexico Department of Health mailed bulletins to 2,400 local doctors and dispatched investigators to interview staff people at clinics and hospitals throughout the northwest corner of the state. By May 29, the CDC had assembled a national team of pathologists, epidemiologists and infectious-disease specialists to aid in the search for a cause. Until last week they hadn’t found a clue. Working out of a dozen labs around the country, the researchers first tested victims’ tissue samples for the germs that cause anthrax, bubonic plague and other bacterial diseases. None of the tests yielded anything. Nor did a search for such common viruses as influenza and chickenpox.
The break came when researchers at CDC headquarters in Atlanta found antibodies to Hantaan virus in tissues from three of the 18 UARDS sufferers. The rodent-borne virus strikes hundreds of thousands of people in Asia each year, causing a flulike illness that can lead to internal bleeding, shock and kidney failure. In China alone, diseases associated with Hantaan kill 200,000 people annually, and experts have long worried that it could gain a foothold here.
The CDC’s preliminary finding doesn’t prove that Hantaan is to blame, but the virus fits neatly into the puzzle. The Navajo reservation, with its abundant field mice and its simple dwellings, is an ideal setting for a Hantaan outbreak. And UARDS has spread like a rodent-borne disease: new cases have cropped up sporadically over a large area, not in the tight clusters you would expect if people were infecting each other. What’s strange is that the Hantaan virus normally attacks people’s kidneys, not their lungs. If the virus is to blame, it has apparently learned a deadly new trick.
While scientists work to close the case, state health officials are taking no chances. They’re urging people not to sweep up mouse droppings, disturb rodent burrows or ingest herbal medicines that could have been contaminated in the field. The CDC, meanwhile, is sending rodent-control experts to the Southwest and distributing antiviral drugs that may help treat the infection. Officials are hopeful that the worst of the epidemic has passed. No new cases were reported last week, and the patients still fighting the illness were making progress. “We’re leveling off,” says Koster. For now, people throughout the Southwest can only hope that he’s right.
